# Tagged Questions

The property of an object that determines how much it responds to a force in Newtonian mechanics, and how much it interacts with gravity in the Newtonian framework. Mass also refers to the intrinsic energy of a particle in particle physics.

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### What really is force? [duplicate]

I know the second law of Newton says $F=ma$ which seems to me the most fundamental expression of the force. In other words, force cannot exist without a "forced" one. It is somehow a "secondary" being,...
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### What am I missing on my thougth expierement? [on hold]

Before I say my thought experiment I wanted to state that most of my knowledge on physics and such is from college books, and not from actual instruction. I arrived at this conclusion and realized I ...
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### Does mass compress space-time?

My understanding of relativity explains that the presence of mass warps space-time so that light travelling through the warp follows at straight line but the warp itself is curved and therefore the ...
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### When Does Mass Matter? [on hold]

I have been trying to wrap my head around this idea for a month or so, and I am not really sure how mass plays into the velocity of a moving body. I have not taken physics in a while, but one thing I ...
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### Does center of mass affect how an object falls?

Suppose you drop an object which has two ends, of which one is heavy and the other is pretty light. Will the object fall with its heavier end downward or with the lighter one? Why does it happen?
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### Does the factor $k$ in Hooke's law change in special relativity? [on hold]

let's say an object is tied to a spring and it's oscillating. But this system is moving in 0.5c. Then, the period of this oscillation increases. But the problem is $k$. I think the $k$ increases ...
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### Photon Mass Term in Schwinger's 2D QED Model

Why does the vacuum polarization in 2D massless Fermion QED, $$i\Pi^{\mu\nu}(q) = i(\eta^{\mu\nu}-\frac{q^\mu q^\nu}{q^2})\frac{e^2}{\pi},$$ have the structure of a photon mass term, as is ...
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### Can we work out how fast we are traveling by looking at our mass?

If we (the galaxy) were traveling close to the speed of light; relativity says we would need proportionally more energy to go faster. Given that relative to the cosmic microwave background, the Local ...
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### Lepton masses in the Standard Model

Some simple questions regarding leptonic masses in the Standard Model (SM): Why there is not an explicit mass term in addition to the effective mass term that arises from the Yukawa terms after ...
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### Do all the particles acquire mass in the Standard Model due to the Higgs mechanism only?

I know that a mass term for an intermediate boson is not compatible with the gauge symmetry. But in principle a mass term for the electron field does not violate a gauge symmetry. However to build an ...
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### Do massless particles really exist? [duplicate]

I was in doubt, so I went to wikipedia. There it says "the photon has zero rest mass", but on the side description it says the mass is $<1.10^{-18} \:\mathrm{eV}/c^2$. So is the mass of the photon ...
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### Why isn't mass conservation counted among the laws of thermodynamics? [closed]

Is this purely a historical artifact, a consequence of how the original formulators of the three laws were thinking and experimenting at the time? Or is there a compelling scientific/logical reason ...
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### SI Base Unit definition of mass - obsolete?

According to the formal definition of the SI Base unit of mass, the kilogram, it is stated that "The kilogram is the unit of mass; it is equal to the mass of the international prototype of the ...
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### Does inertia increase with speed? [duplicate]

I have heard that when the speed of the object increase, the mass of the object also increase. (Why does an object with higher speed gain more (relativistic) mass?) So inertia which is related to ...
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### Why do we still not have an exact definition for a kilogram?

I read that there is an effort to define a kilogram in terms that can exactly be reproduced in a lab. Why has it taken so long to get this done? It seems this would be fairly important. Edit Today I ...
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### I know that free fall in vacuum is independent of mass. But what happens in air?

Pardon me if this sound somewhat trivial to some of the highly qualified users here. So I know two objects will fall at the same rate if they are in absolute vacuum, so what I'm assuming is that the ...
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### Are neutrinos affected by gravity?

Layman here, but EE and BS physics. I know that light is affected by gravity. But are neutrinos? During the collapse of a star into a neutron star, as the electrons join protons to form neutrons (e....
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### Does the increase of (relativistic) mass, while flying near speed of light, has any impact on astronauts? [duplicate]

Possible Duplicate: Would travelling at relativistic speeds have any impact on human biology? I am asking myself this question for a few days. What is the correct answer on: Does the increase ...
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### Trouble understanding the concept of true and apparent weight

I need help understanding the concept of true weight vs apparent weight. I understand this much: if someone is standing in an elevator on a scale, the further up they go the less the reading on the ...
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### Why not $\rho^{2}=T^{\mu\nu}T_{\mu\nu}$ as an effective mass density (squared ) in general relativity?

Why not $\rho^{2}=T^{\mu\nu}T_{\mu\nu}$ as an effective mass density (squared) in general relativity? It's covariant, and as far as I can tell is zero for any electromagnetic field tensor. \begin{...
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### Why neutrino is always left handed

Why all neutrinos are always left handed while all anti-neutrinos are right handed.
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### Maximum “size” of a galaxy

I am aware of upper limits to the mass of burning stars and neutron stars, beyond which they degenerate into neutron stars and black holes respectively. And also, if I understand it right, there is a ...
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### Can we give particle with no mass, mass? [duplicate]

Is it possible to take a particle with no mass and give it mass. For example light? Or increase mass?
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### Can someone please give some references on scattering in Proca theory?

Can someone please give some references on scattering in Proca theory? I am looking for scattering calculations with massive photons.
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### How do the right-handed fermions acquire mass?

I am constructing a presentation on how elementary particles acquire mass via interaction with Higgs field. I asked this question previously in a different form and received the usual clap trap, so I ...
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### most efficient set of weights with whole number mass to n-power for balancing unknown mass on vertex of regular triangle

I saw this qustion: http://puzzling.stackexchange.com/questions/186/whats-the-fewest-weights-you-need-to-balance-any-weight-from-1-to-40-pounds Suppose you want to create a set of weights so ...
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### Can light change the shape of a black hole?

If light orbits a black hole without ever getting closer or further from it, and the black hole pulls on the light from all directions nearly simultaneously, does the black hole extend at its equator? ...
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### What exactly is the relationship between gravity and acceleration?

I know that one of Einstein's key steps towards General Relativity was the realization that gravity and acceleration were related. I understand the free-falling elevator analogy, but the relationship ...
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### Bondi mass aspect

I'm looking for a good reference that defines the Bondi mass aspect and his relations to Bondi and ADM mass. Googling a bit I've not founded any satisfactory exposition of the subject. A short ...
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### Can a superpartner be less massive than its SM counterpart?

Theoretically, can a superpartner be less massive than its standard model counterpart? I realize there are experimental constraints.
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### How did physicists conclude that 98% of mass is due to the strong force?

On a video on YouTube called 'weak and strong nuclear force (9/15)' at 0:55 a scientist said that 98% of mass is due to the strong force.
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### What is the connection between inertial/gravitational mass and relativity?

In Einstein/Infield 's The Evolution of Physics (32-35) the authors establish that inertial mass and gravitational mass are the same and then connect this to relativity.Throughout these pages I was ...
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### Acceleration in $F=ma$

I tried to ask this question in Electrical Engineering Stackexchange but was told I was better asking here. Newton's Second Law of Motion states that the vector sum of the forces $\mathbf{F}$ on an ...
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### Effective mass vs. effective charge

In a semiconductor the effective mass multiplying the drift velocity is the result of the scattering of electrons off the ions in the crystal. I know that at least in the lowest order approximation ...
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### Sound level of organ pipe driven by helium

The sound pressure level of an organ pipe is a function of the gas flow rate delivered to the pipe. Source Would the sound level of an organ pipe driven by helium be lower than that of a pipe driven ...
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### Working out a specific charge of an atom?

I know how this formula work if the mass of the nucleus and the charge of the nucleus is given, however I do not understand how they get them as I have two books which do it differently. So the ...
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### Kaufmann's experiment 1902

Kaufmann's experiments (1902): http://en.wikipedia.org/wiki/Kaufmann%E2%80%93Bucherer%E2%80%93Neumann_experiments#Historical_context About charge to electromagnetic-mass ratio. Fig 2 has a plot of ...
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### Atomic Weight and Time Dilation

So, this might sound kind of ridiculous but I was thinking about Relativity and since Gravity is a warping of Space-Time, or Time Dilation, why don't we measure Atomic Mass in Units of Time Dilation? ...
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### Does massive particle really move at speed of light? [closed]

According to this answer I understood that particles with mass also move at speed of light but interaction with higgs field make this movement zigzag. So average speed is below speed of light. Is ...
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### Interpretation of the mass of the field

Before QFT I had never thought if a field should or should not have any mass. Now it turns out that either case is possible. It might be naive to think this way, but I picture the mass of the field in ...
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### How to determine the overturning moment on a stand alone, uncovered bean pole tipi

I will preface this by saying I am a highschool student who has not yet had a physics class. I engineered and built a hexagonal shaped, open bottomed, planter to hold soil that would contain pole ...